How can I make a 3 AA rechargeable batteries powered device last longer?

I got a battery powered plastic cutter ( the batteries were used to heat the blade) and turned it into a soldering iron. I thought it being really smart of me, but the power of my 2700mAh batteries is severely not enough to melt the solder for long. Ater 15 minutes' work it simply stops melting, while the batteries are still fully charged, so my charging device simply turns the green light on and refuses to charge them. HELP!!!

That's all very nice, but somehow my parents don't like anything "Lighter gas" powered, so the battery thing was my solution to avoid it. (I even use an ethanol burner instead of a Bunsen burner despite the fact its very hard to get ethanol here, or anywhere, I suppose, but I don't know why it is safer).

Wow, but "if it is to be used on electronics, one should be well aware of how the device works and the sensitivity of components being soldered" and "the tip is very fragile", so even if I find it anywhere, it'll cost loads and loads of money (I earn nothing), and I will either brake it on the first day, or be too afraid to do anything with it (not exactly my idea of fun).

Well, I'm not sure if it's *that* fragile, but you're probably right about the cost. If you can't get it locally, it'll probably cost a bundle! I say you should try to convince your parents to let you get a butane powered soldering iron. They heat up fast, and last for hours. They are safe to use - the flame is not exposed like on a lighter.

Cool! Is that the case for all of them, or just the higher end models? I've seen some "convertible" models in which you can remove the soldering tip to get a regular torch - in that case, the torch just heats up the tip.

Thanks, but the problem is that I need a soldering iron that is able to function without a mains power supply for at least an hour of work ( it doesn't have to be on all that time as it heats up quite quickly). I badly need it on various in- the-fields summer school, where you are supposed to do Physics experiments, but the power supply is one or two half-dead sockets and they don't allow you to sit there and solder for long, or even use them for something more power-consuming than a phone charger (for example making tea is a problem :) )

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Bio:I love doing practical things about science, but, sadly, it is not quite what you usually learn at school, so for the last 8 years of my life I remained the only crazy kid who has a closet full of met...read more »